Normal map visualization in Metashape Pro

[Limpopo_River]

I've generated normal maps of archaeological objects using Metashape Pro (v. 1.6.6) and I'm unable to see any detail when viewing the normal maps in the model window.  I used the arbitrary 3D mesh processed at "ultra-high" resolution as the source for the normal maps. The normal maps appear to be completely uniform in color, with no discernible features.  I'm trying to understand if there's a problem with the normal maps themselves or if it's just a problem with the visualization of the normals in the model window.  Has anyone had a similar experience viewing normal maps generated in Metashape and/or can you suggest a reason for the absence of any detail in the visualization?

[wojtek]

If it's plain color you're probably baking meshes very close density wise.

Is your target mesh considerably less dense than your source mesh?

[Limpopo_River]

Thanks Wojtek, you've pointed me to the right explanation.  However, I wasn't attempting to bake the normal map onto a lower-resolution mesh, I only wanted to visualize the normals of my 3D mesh at the full resolution in the Metashape model window.  The mesh has 34 million faces and 17 million vertices.  Another question is whether the normal map generates normals from the faces or the vertices?

I notice that when I generate the normal map, Metashape automatically decimates the mesh from 34 million to 1 million polygons.  There doesn't appear to be a setting one can use to avoid decimating the mesh when generating the normal map, unless I'm missing something.  Could you or anyone suggest a way to generate the normal map without decimating the mesh?

My objects are relatively flat, so what I'm hoping to see in the model window would look something like a map of normals to the 3D mesh surface projected onto a 2D plane, like an orthomosaic or DEM with normals for each pixel.  Because my high-res mesh is relatively flat overall, despite having a lot of surface variation, the normal map appears to be a uniform color when the mesh is so heavily decimated.